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Nuforce P-9 Preamp
A Rhapsody of Fluidity

 

 February 2009

 



   


Back in the spring of '06 I did a follow-up to Frank Alles' wonderful review of the Nuforce 8's. Life has been grand living with Nuforce's latest and greatest design in their Ref 9SE amplifier. So be it, when the opportunity came to hear and possibly review their highly anticipated two-chassis P-9 preamplifier - driving the Ref 9SE's no less - I jumped at the opportunity. 

The Nuforce P-9 preamplifier is a unique two chassis, cable-connected design. Each of the two boxes is a rack-friendly, measuring 1.75”H x 8.5”w x 16”D, and they are connected to one another by an included control cable. As the manufacturer’s web site explains, “One chassis contains three power supplies and microprocessor control logic; the second chassis contains an analog volume control, input selection relays, and sensitive analog circuit components.”

The unit I reviewed was silver-color anodized aluminum with a sandblast finish. Stylistically it mated beautifully with the black Nuforce P9 monoblocks in my system. In comparing the black to silver, the latter is even more impressive and eye grabbing, with its hint of a gleaming sheen.

Each of the P-9’s two chassis’ has its own volume control, one digital, the other a manual Alps potentiometer. The digital control is not a digital volume control in the usual sense of the term, as the audio signal never exists in the digital domain. Rather, the digital microprocessor controls the analog potentiometer’s motor in the other chassis, the two being connected by a supplied cable. The chassis with the digital microprocessor not only receives the remote’s input and passes it on to the analog chassis but also features memory for storing the last used input selection and volume level at shut-off and turn-on. The most readily apparent, distinctive and perhaps somewhat curious feature of this arrangement is that the volume can manually be controlled by turning the control knob on either chassis. This arrangement is the end result of Nuforce’s design choice of moving the sound-sullying remote circuitry away from the analog pot into its own separate chassis to preserve the performance of what is essentially an analog volume control. In making manual adjustments I preferred the smoother feel of turning the analog pot rather than the digital volume control.

The P-9’s amplifier module is all-discrete, with the final voltage amp comprising ultra-low noise, monolithic dual JFETs, specially selected VMOS FETs and extremely flat hFE bipolar transistors in a dual cascade arrangement. According to NuForce, these features give the P-9 a 5 MHz bandwidth, a S/N ratio exceeding 100 dB and a dynamic range better than 120 dB. Its gain circuit has no capacitors or DC-servos in the signal path.

Nuforce has gone so far as to thermally insulate the P-9’s amp modules inside heavy copper shields to prevent the intrusion of performance-degrading thermal drift or signal-related heat production. Each amp module has its own self-contained shunt regulator to further isolate it from the power supplies. Another distinct and isolated floating-current source supply feeds each module to further separate them from the noise in the ground system. The control system sends only DC to the relays and the potentiometer’s motors. None of the logic circuitry is allowed to introduce noise to the delicate signals working in the analog section of the device. According to NuForce, these factors contribute to an extremely low noise floor.

The P-9 also has a bypass system for those desiring to integrate a home theater setup into a high performance audio system that can connect the power amps for the main speakers directly to the AV processor or AV receiver amp, thus allowing for an unfettered transition from the most demanding 2 channel audio playback to THX or similar multi-channel surround-sound with bass management.
Lastly, the P-9 has 5 pairs of RCA inputs, one pair of RCA and one pair of XLR outputs for balanced connection.

Setup, User Interface and Remote

Because of its small profile, physical set up was easy. I tried the boxes in both side-by-side and stacked configurations, ultimately preferring the look of the latter. Even though having them side-by-side and as far apart as possible to aid in isolation should have theoretically yielded the best sonic results benefits, I didn’t perceive any degradation in sound by having them stacked.

I interfaced the P-9 to the outstanding Nuforce Reference 9 V2 SE monoblocks via unbalanced RCA interconnects, and filled up 4 of its 5 inputs with a Marantz SA 15s1 SACD player, a tuner, a network uncompressed audio player, and a pro-level portable digital audio recorder. The RCA connectors on the back of the P-9 are of the heavy duty gold-plated type that I like to see on units in this price range. All tolerances and the soundness of connections were excellent. I was also happy to see that the RCAs were spaced far apart enough to accommodate the rather large twist-lock male connectors of my Straightwire Crescendo interconnects. With what I had on hand at the time, I achieved the best performance in my system using Analysis Plus’ Power Oval 2 to feed power to the P-9.

Powering on and off the device was simple from the remote. Startup and shutdown could also be performed from the control unit itself by pressing in the input selector knob on the microprocessor chassis and holding it in for a couple of seconds. This feature was not obvious as there was no text or icon indicative of this ability on the chassis. (I received the unit from Clement Perry without a manual and perhaps this feature would have been more obvious if I had the manual to consult.)

Selecting sources, changing volume, muting and powering off and on the device were all simple using the substantial and strikingly shaped remote. At the flat-sided, front end of the remote is a protruding bulb for sending the infrared signals. This configuration at first glance seemed possibly prone to breakage but the bulb was solid and perhaps of the LED type. I must note that the remote, though substantial in weight, is designed such that dropping can lead to its coming open at either end. I had to fix this problem a couple of times as the remote slid off my listening ottoman where most of my remotes tend to reside. The repair was easy enough each time but this aspect of the remote’s design could be improved.

Listening
Just a week prior to making my final listening notes I was on a clinic performance with vibraphonist Stefon Harris’ band as part of a seminar at the Chamber Music America’s New Music Institute at the University of Buffalo in Amherst, NY. We had the great pleasure to conduct the clinic in conjunction with the terrific Ying Quartet. Both ensembles showed and discussed compositional and performance concepts relating to new music within our specific genres.

The Yings makeup a tightly knit string ensemble comprised of 3 brothers and a sister. Sitting 2 rows back dead center with no one in front of me listening to that string ensemble not even 15 feet away perform Lei Lang’s “Gobe Gloria” was a treat I’ll never forget. Immediately thereafter I purchased their CD Dim Sum (Telarc CD-80690) to regain some of that magic I heard there that day in that small theater.

At first listen to the “Gobi Gloria” from the Ying CD with my reference Monolithic Sound PA-1 Line Stage, I felt I was being cheated. The flesh and subtle majesty I heard in live performance was nowhere in evidence on the CD. Aside from the fact that the ensemble had rehearsed several times before performing the piece, I felt there was a lifelessness and flatness to the CD (in the worst sense of the word) that just would not allow me to sit back and enjoy the music.

The Lei Lang piece is built around Mongolian folk music and there is a specific cultural soulfulness in the Ying’s performance of Gobi Gloria that can be sensed on probably a lot of decent systems. With the P-9 in place sensing went from that, to truly feeling.

Substituting the P-9 for my PA-1 brought an immensely richer harmonic soundscape with a supremely quiet noise floor. The tonal palette throughout all registers was afforded much stronger and more believable fundamentals particularly from of the cello. Micro dynamics were conveyed with naturalness and lifelike precision that gave a mesmerizing ebb and flow from the music that I remembered hearing in the live performance. The soundstage depth and width were more cohesive and realistic than what I had been experiencing with the Monolithic.

All of these positive aspects of the P-9 combined to impart more of a human feeling to the recording. At last the magic I heard when listening live to the Ying Quartet was beautifully intact via the P-9.

In my earliest listening to the P-9 I felt that the highs might have been a bit rolled off, particularly with cymbals, and that as such its soundstage rendering and depth might not have been quite up to snuff to other areas of its performance. Fortunately for me and you the readers, our fearless leader, Clement Perry dropped by with some extra cabling options for me to pair with the P-9. Putting the ultra expensive AC power cord from White Gold Electronics’ Prestige ‘M’ Series ($2500) onto my Marantz SA 15S1 in place of a ($200) Analysis Plus Power Oval delivered a wealth of additional upper register clarity and weight to my system.

In listening to “Two Pieces of One: Green” from Tony Williams’ special RVG Edition of Life Time (Blue Note Records 7243 4 99004 2 4) what had been a trick of “explosiveness” in my previous setup of preamp and power cables had become with the P-9 an explosive musicality. The P-9, with a more suitable combination of cables, rendered Tony’s cymbals with immensely more lifelike precision and more weight. Sam River’s tenor sounded considerably richer, more fleshed out and enveloping than what I have ever heard before in my system. The most striking realization (and in the most subtle of ways) was that I was now able to track each player’s ideas and musical dialogue with one another, more so than with virtually any system I have heard.

The resolution of macro and micro dynamics was astounding in its scope and breadth. The midrange was now more convincing, meaty and articulate. All of these combined to allow me to suspend disbelief for a while and sink into the music more than I have ever done before. [Ever before, or ever before with your system as it is?]

Count Basie’s “Blues in Hoss’s Flat” from the Chairman Of The Board CD (Roulette Jazz 7243 5 81664 2 2) revealed the P-9’s knack for serving up oodles of effortless pace, weight and authority. I didn’t have any sort of technical measuring capabilities at my disposal but I feel safe to assume from my listening, that the P-9 has vanishingly low levels of distortion which allowed this recording to shine throughout with a believability that had me glued to every musical twist in turn like never before. Aside from the gut-smacking dynamics I was most struck by Basie’s piano sounding immensely life-like, liquid, and weighty in all the best connotations of the word.

As much of a delight as was already had, the enjoyment factor went off the charts when I turned my ear to the RCA Living Stereo SACD of Ravels’ Daphnis and Chloe (BMG Classics 82876-61388-2 RE1) as performed by the Boston Symphony (conducted by Charles Munch). The P-9 showed an excellent delineation and clarity to Ravel’s orchestral layers. Once again the P-9 uncannily tracked the individual parts without ever sounding etched. The violins took on that sweet shimmering and fleshed-out quality reminiscent of life music.

My attention kept jumping from part to part as each came and went, the P-9 differentiating and sewing everything together in an exquisitely musical way. The spread of the orchestra and chorus across and throughout the soundstage via the P-9 was entirely appropriate, lifelike and beguiling. Voices sounded fleshy as they should; tambourines and triangles sparkled as they should; and snares rasped as they should. Ensemble strings had weight when appropriate; contrabass violins had body-enveloping resonance when the should; and forzando bass drum articulations had earth-moving depth and impact when appropriate.

To test out the P-9’s funk and groove factor, I indulged in some modern day funk courtesy of Erykah Badu’s “The Cell” from her New Amerykah, Part One: 4th World War CD (Universal/Motown B0010800-02), so as . At a booty-poppin’ party level, the Nuforce laid it on thick and greasy with nary a hint of stress or edginess. Stephen “Thunder Cat” Bruner’s bass took on a great deal more propulsion and solidity than I had ever heard from this CD prior to my time with the P-9. Still, in the midst of all this churning bass, pop synths, funk drums and percussion, Ms. Badu’s vocals were afforded a greater level of intelligibility to her typically less than clear enunciation. This is one of my pet peeves with modern R & B recordings in that they tend to hype the level of the background tracks such that the lyric can barely be discerned. Somehow, the P-9 sorted it all out and set all the parts in musical balance.

Conclusion

My time with the P-9 was an absolute joy for me and a select few who dropped by for a listen. It’s synergy of excellent fluidity, unbridled macro and micro dynamics with a naturally hefty midrange, extended highs, authoritative lows as well as apparently extremely low amounts of distortion, have placed the P-9 at a truly reference level. It possessed an alluring amount of ebb and flow that allowed me to forget I was listening to electronics and simply put the music up front and center.

The P-9 has the astounding musical treasure of allowing me to hear more of each individual part but never at a sacrifice of the whole. With as much differentiation and delineation I heard, I felt it imparted greater musical meaning to the whole of each performance. Never once did I grow weary or suffer from audio fatigue with the Nuforce in place.

Was the P-9 perfect? Probably not, but I can’t honestly say what I would have improved in terms of its audio performance. For owners of Nuforce amps, the P-9 is most probably THE preamp to get or if not, at least THE preamp to audition as a reference point for those looking in the $3,500 range and above.

 

                             


Specifications:

• Inputs: 5 RCA (including Home Theater bypass input
• Outputs: 1 RCA, 1 XLR (XLR output is unbalanced)
• THD+N at 1kHz = 0.0004% at 20-20kHz = 0.003% at DC to 1MHz: < 0.05 %
• S/N = 100dB at 20-20kHz S/N > 90dB at DC to 1MHz
• Frequency Response at 20-20kHz = +0.02dB/-0dB at DC to 1Mhz = +0.5dB/-0dB at DC-2.5 MHz +0/-3dB
• Maximum output: 7V RMS
• Phase shift = 0
• Input impedance = 10K ohm
• Output impedance = 100 ohm
• Dimensions: 1.75”H x 8.5”W x 16”D
• Weight:
• Power 120V 60Hz (100V and 240V models available)
Chassis available in black, silver or rose copper color anodized aluminum
3 year warranty

Price: $3,500.00


Address:
Nuforce, Inc.
356 South Abbott Ave
Milpitas, CA 95035
Telephone: +1-408-627-7859 or 1-408-262-6777
Fax: 1-408-262-6877
Email: salesteam@nuforce.com

Website: www.nuforce.com
 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

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